When a silver halide photographic material is exposed to light and is subjected to color development processing, a developing agent, such as an aromatic primary amine, is oxidized with the silver halide to react with dye-forming couplers to form a color image. Generally in this method, the color reproduction is often effected by the subtractive color process, wherein in order to reproduce blue, green, and red colors, yellow, magenta, and cyan color images complementary to them are formed.
As cyan color image forming couplers, phenols or naphthols are used in many cases. However, concerning the preservability of color images obtained from conventionally used phenols and naphthols, some problems remain unsolved. For instance, color images obtained from 2-acylaminophenol cyan couplers described, for example, in U.S. Pat. Nos. 2,367,531, 2,369,929, 2,423,730, and 2,801,171 are generally poor in heat fastness; color images obtained from 2,5-diacylaminophenol cyan couplers described in U.S. Pat. Nos. 2,772,162 and 2,895,826 are generally poor in light fastness; and a 1-hydroxy-2-naphthamide cyan coupler is generally unsatisfactory in both light fastness and heat (particularly heat and humidity) fastness.
Further, the cyan dyes obtained from these couplers have undesirable absorptions in the blue and green regions and therefore have a serious problem that lowers color reproduction remarkably, which is desired to be solved.
As means of solving this problem, imidazole-type cyan couplers described in EP (European Patent) Nos. 249,453A, 304,856A, 320,778A, and 354,549A, pyrazoloazole-type cyan couplers described, for example, in U.S. Pat. Nos. 4,873,183 and 4,916,051, pyrazolopyrimidine-5-one and pyrazolopyrimidine-7-one-type cyan couplers described in EP No. 304,001A, and pyrazoloquinazolone-type cyan couplers described in EP No. 329,036A and JP-A ("JP-A" means unexamined published Japanese patent application) No. 166446/1990 are mentioned. However, these couplers cannot solve the above problems fundamentally because, for example, these couplers are poor in the coupling reactivity with the oxidized product of a developing agent, they are poor in the spectral absorption characteristics of the obtained cyan color image (for example, the maximum absorption wavelength is too short, there is a certain level or over of undesirable absorption in the blue region or green region, or a satisfactorily effective absorption coefficient is not present in the long wavelength side), and they are poor in the stability of the cyan color image against heat, humidity, or light.
As another way of obtaining a cyan color image having preferable spectral absorption characteristics, a technique wherein the phenomenon of association, cohesion, or crystallization of dyes is used is mentioned. For example, an image-forming method is disclosed in U.S. Pa. No. 3,002,836 wherein a silver halide photographic material that has been exposed to light is developed with a developer containing an alkali-soluble 1-naphthol-type cyan coupler having the following specific structure: ##STR2## to obtain cyan development.
In this image-forming process, the produced indoaniline dye is immobilized by association, cohesion, or crystallization in the gelatin film, and it gives a cyan color image quite small in undesirable absorption in the blue and green regions and having excellent spectral absorption characteristics in view of the color reproduction. This method is applied to Kodachrome that uses the so-called coupler-in-developer-type development and gives a fast cyan color image excellent in tone. However, this method is defective in that it cannot be applied to the coupler-in-emulsion-type system, for example, for color negative films, color reversal films, and color papers which is currently mainly used.
As a technique of overcoming this defect, means is disclosed in JP-A No. 108662/1980 wherein, for a coupling-off group (a group capable of being released upon a coupling reaction of the coupler with the oxidized product of a color developing agent) in the 4-position of 1-naphthol, a coupling-off group that can render the coupler nondiffusible is selected to make the coupler immobilized in the photographic material, and also a silver halide color photographic material is disclosed in U.S. Pat. No. 4,960,685 wherein the above means is combined with a specific magenta coupler and yellow coupler. However, the cyan image obtained from such a cyan coupler has a defect that generally the tone is liable to change with the lapse of time due to heat, light, and humidity, and improvement is desired.
JP-B ("JP-B" means examined Japanese patent publication) No. 14523/1975 discloses a photographic material that contains an N-phenyl-1-hydroxy-2-naphthamide-type cyan coupler whose benzene ring is substituted by a carbamoyl group or amido group having a long-chain alkyl group with 10 or more carbon atoms. However, the tone of the cyan image obtained from these cyan couplers is also liable to change with the lapse of time.